Relay.



PATENTED MAR. 17, 1903-. w. w. DEAN. I

RELAY.

APPLICATION FILED JULY 20, 1900.

2 SHEETS-SHEET 1.

N0 MODEL.

m w m No. 722,680; PATENTED MAR. 17, 1903 W. W. DEAN.

RELAY.

APPLICATION FILED JULY 20, 1900- no MODEL. 2 SHEETS-SHEET 2.

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UNITED STATES PATENT OFFICE.

WILLIAM W. DEAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE WESTERN ELECTRICCOMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

RELAY.

SPECIFICATION forming part of Letters Patent No. 722,680, dated March17, 1903. Application filed July 20, 1900. Serial No. 24,339. (Nomodel.)

To ail whom it may concern:

Be it known that I, WILLIAM W. DEAN, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented a certain new and useful Improvement in Relays, (Case No. 34,)of which the following is a full, clear, concise, and exact description.

My invention is a relay adapted for response to pulsating or alternatingcurrents such as are employed in calling over telephone-lines, and isdesigned especially for employment at substations of telephone systemsto temporarily connect a polarized callbell with the line to receive theincoming signal when the relay is affected by such current.

The object of the invention is to produce a relay which shall maintainsecure contact at its switch-points during the existence of thecalling-current even though the latter may be of intermittent character,to be silent in its movement in response to the exciting-current, to beofsimple and durable construction, and capable of accurate manufactureby means of simple processes.

My relay is designed especially for use in connection with a party-linetelephonecircuit of four stations wherein the relay is connected in abridge of the line-circuit at each station, together with a condenser,and serves when affected by calling-current to connect with one or theother of the line conductors should also be silent in its action inorder that no sound may be made at those stations which are not intendedto be called.

. The attached drawings illustrate my invention.

Figure l of the drawings is a diagram showing the circuits of thefour-station party-line extending to a central office of a telephonesystem with means in the switchboard at the central office forselectively calling the different stations. Fig. 2 is a side elevationof my improved relay. Fig. 8 is an end view thereof. Fig. 4 is a plan,and Fig.- 5 is a sectional view showing the position of the armaturewith relation to the core.

I will first briefly describe the circuit arrangement in which the relayis designed to be operated.

The two line conductors 1 and 2 of the partyline circuit extend from thespring-jack a of the telephone-switchboard to each of the stations I,II, III, and IV. At each station a bridge 3 of the line-circuit isformed, which includes a condenser 19 and the magnet of the relay 0.This relay is of high resistance and is constructed to have speciallyhigh impedance in order that telephone-currents may not be divertedthrough it. It may have a resistance of two thousand ohms and may havefifteen thousand turns of wire upon it. Each of the relays controls theconection with the line-circuit of a call-bell, the bells at thedifferent stations being designated 05, d (Z and C1 The bell d atstation I is in a ground branch from the line conductor 1 and ispolarized and biased to respond to positive current. The bell (Z atstation II is likewise connected with line conductor 1, but is polarizedto respond to negative current. Bells d and d at stations III and IV arebiased for negative and positive current, respectively, and areconnected from line conductor 2 in ground branches, which are controlledby the relays c at the same stations. Each station is also furnishedwith telephone instruments and a telephone-switch for connecting themwith the line-circuit.

In the central office the calling-plug in the switchboard for makingconnection with the line by means of its spring-jack is connected with aseries of calling-keys, which are adapted to apply pulsating currents ofdefinite polarity to either of the two line conductors.

Thus the key 6 is arranged to apply positive pulsating current to lineconductor 1 for operating the bell at station 1. Key 6 applies anegative current to the same conductor, while keys (2 and 6 applynegative and positive pulsating current to line conductor 2,respectively, for ringing the bells at stations Ill and IV. Each of thekeys while applying current to one line conductor is arranged to groundthe other line conductor, being thereby adapted to divert through theground branches of the latter line conductor the current reaching thatline conductor through the bridges at the different stations, so toprevent the ringing of bells not directly connected with the lineconductor to which the calling-current is sent. Thus the line oonductorsare normally free from ground branches which would tend to disturb theinductive balance of the telephone-line; but the act of sendingcalling-current in the line of any kind causes all of the relays c toconnect the different biased bells to the line conductor, and thuspermits calling-current to flow through the bell intended to be rung.

My improved relay is specially constructed to have a high impedance, andthus requires a good magnetic circuit.

A further characteristic is found in the armature of great inertiahaving a wide range of movement, whereby it is prevented from followingthe quick pulsations of the intermittent current and takes and maintainsa definite position during the transmission of the intermittentcalling-current.

The relay consists of a core f, with the wire f wound thereon, a returnmagnet-circuit or a pole-piece g, and the armature hof U shape. Thedownwardly-projecting ends of the U -shaped armature embrace extendedpole-pieces and are pivoted at their lower ends on trunnions h hentering brass bearings g 9 sunk in the two sides of the polepiece g.The armature is made heavy to have great inertia, and by reason of thegreat length of its radius of movement it is capable of a wide range ofmovement without a great elevation of its center of gravity. The ends ofthe pole-piece g conform to an are drawn from the pivotal points g g sothat there is no change of magnetic potential between the pole-piece andthe armature during the movement of the latter. The polar extremity ofthe core f isinclined and curved to produce a gradual diminution of theresultant magnetic potential between the core and the armature as thearmature approaches the core until the armature comes directly over thecore, at which point the armature is subjected to only a very feebleforce urging it to a further movement, the pull being directly downward.The tendency of the armature to tremble under the influence ofalternating or pulsating currents exciting the magnet is thus reduced toa minimum. The movement of the armature is begun under the influence ofa considerable attractive effort, which as the armature swings forwarddiminishes and changes in direction till nearly the whole effort of themagnet is directly downward, the armature being carried to this point byits inertia.

The heads of the magnet-spool are formed of square blocks t' and t",which fit closely within the space between the two extensions ofpole-piece g. The upper extremities of the pole-piece are secured to theopposite sides of the block 'iby means of screws passing into the block.This head '1 carries two posts 7c it, which are covered with felt andwhich are located in position to form limitingstops for the movement ofthe armature h. The same block of insulating material carries theterminals of the magnet-spool.

The contacts of the relay consist of an adjustable contact-screw Z,passed through the flattened portion of the armature near its pivotalpoint, and the contact-spring m, carried upon a bracket '21, secured byscrews passing through plates of insulating material to the pole-pieceg, the spring and bracket lying substantially parallel to the armature hwhen the latter is in its attracted position. The bracket underlies thespring and forms a normal resting-stop therefor. A stud 0, secured inthe bracket, passes through an opening in the contact-spring m andcarries an adjusting-nut 0, which may be brought to bear against thespring to vary its tension.

When this relay is subjected to pulsating current, the armature startsgently from its resting-stop by reason of the feebleness of theattraction of the core over the great intervening distance. lVhen thearmature has reached its forward position, the attraction upon it isdownward and tends to produce no further forward movement, so that thepulsating current causes at most only a slight tremor of the armature.For these reasons the appliance is silent in its operation.

The contacts Z and m are located near the pivotal point of the armatureand are closed in the initial movement thereof, so that they are firmlyand continuously closed while the armature is attracted.

In the construction and assembly of the appliance the parts may bepressed from material in sheet form, with the exception of the core, andas the distance from the inner face of the armature to the pivotalpoints and the length of the core constitute the only dimensions whichmust be closely adjusted the parts may be readily assembled withoutliability to inaccuracy or defects in adjustment.

I claim as new and desire to secure by Letters Patent 1. The combinationwith a telephone-line extending from a substation to a central office,of a call-bell at the substation in a normally open branch, means at thecentral office for applying intermittent calling-current to the line,and a relay at the substation, said relay comprising a core f, amagnetizing-helix therefor included in the path of the callingcurrent, aU-shaped armature h of great inertia having its arms pivoted at theirends in the line of the core and normally lying in a plane inclined tothe axis of said core, said armature being swung into the plane of thecore when the magnet is excited, the yoke of said armature moving overthe end of the core and relay-contacts closed by the armaturecontrolling the normally open branch which contains the call-bell,whereby the armature maintains a definite position and holds thecall-bell circuit closed during the transmission of the calling-current,as set forth.

2. In an electromagnet, the combination with the central core of theU-shaped polepiece 9 embracing the magnet-spool, the inverted- U shapedarmature h pivoted near the heel-piece of the magnet, the arms of thearmature and pole-piece lying side by side in parallel planes, theyoke-piece of the armature being adapted to move over the polar face ofthe core, as described.

3. The combination with a core, of the U- shaped pole-piece g embracingthe core, the square spool-head t' of the core, the extremities of saidpole-piece being secured to said head, and the inverted-U-shapedarmature h pivoted near the yoke of the magnet, the 1 arms of saidarmature embracing the arms of the pole-piece and moving in parallelplanes therewith, the yoke of said armature extending across thepresented ends of the core and pole-piece, as described.

4. In combination, the core f and magnetwinding thereof, the U-shapedpole-piece g, the inverted- U-shaped armature h pivoted near the yoke ofthe magnet and carrying a contact near its pivotal point, and a flexiblecontact-spring therefor and the bracket secured to the pole-piece gcarrying the said WILLIAM W. DEAN.

Witnesses:

ELLA EDLER, O. GROSENBAKER.

